Police received a call at around 11:30 p.m. Thursday night, which led them to 80 Alton Towers Circle, where they found a woman in her 60s with obvious signs of trauma. She was pronounced dead at the scene.
The building's superintendent told CBC News that the woman lived on the 17th floor of the 20-storey building.
Her identity is being withheld until next of kin are notified.
Police are going through security video and are asking anyone in the building or with information about the incident to contact Det. Mary Vruna at 416-808-4200.